Eyeworld

53 EW RESIDENTS February 2019 as the LenSx (Alcon, Fort Worth, Texas). A high-energy machine may potentially increase MDA concen- tration to the point of statistical significance when compared to conventional phacoemulsification. A study that measures MDA levels and other markers of oxidative stress after phacoemulsification with a high-energy machine is warranted. The major strength of the study is its randomized controlled design, which randomized patients to re- ceive FLACS in one eye and conven- tional phacoemulsification in the other eye. Performing both interven- tions in a single patient reduces con- founders by limiting patient-to-pa- tient variation. However, the study is limited by its small sample size. A larger sample size could have given the study greater power to detect true differences, and borderline and insignificant results in this study could well have become statistically significant. Overall, the study demonstrates that low-energy FLACS has the advantage of decreasing effective phacoemulsification time, while having similar levels of inflamma- tion and oxidative stress at the end of cataract surgery as conventional phacoemulsification. While the risk of intraoperative miosis is higher with FLACS, that risk can be miti- gated but not completely eliminated with the use of preoperative topical NSAIDs. The findings of this study add to the many factors influencing the decision to choose FLACS over conventional phacoemulsification or vice versa, which includes but is not limited to safety profile, visual outcome, and patient preference. By continually reviewing the literature both during and after residency, we will be able to advise our patients on the best treatments and technology available. EW References 1. Takacs AI, et al. Central corneal volume and endothelial cell count following femtosecond laser-assisted refractive cataract surgery compared to conventional phacoemulsifica- tion. J Refract Surg. 2012;28:387–91. 2. Schultz T, et al. Changes in prostaglandin levels in patients undergoing femtosecond levels was significantly correlated with effective phacoemulsification time, which was shown in a separate analysis to be significantly higher in the conventional phacoemulsifica- tion group than the FLACS group. Discussion Since the advent of FLACS, several studies have compared FLACS to conventional phacoemulsifica- tion. The study by Liu et al. is the first to analyze aqueous fluid both after laser pretreatment and after phacoemulsification, which provides insight into the immediate postop- erative inflammatory response in FLACS. After laser pretreatment, the FLACS group had higher prostaglan- din levels than the conventional phacoemulsification group. The addition of preoperative NSAIDs (FLACS-N group) significantly reduced prostaglandin levels and frequency of intraoperative mio- sis, but did not decrease the rise in post-phacoemulsification prosta- glandin levels. The finding that 20% of patients in the FLACS-N group still developed intraoperative miosis implies that other factors aside from prostaglandins may contribute to miosis. Another unique and clinically relevant aspect of this study is its measurement of MDA, a marker of oxidative stress that had only been collected in vitro in prior studies. Oxygen free radicals are created during phacoemulsification and aspiration and irrigation, and can potentially damage the corneal endothelium. 5 This study showed that although oxidative stress was greater in FLACS compared to conventional phacoemulsification, this difference was not significant. FLACS may therefore cause similar levels of oxidative stress as conven- tional phacoemulsification but have the added potential advantage of decreased effective phacoemulsi- fication time due to the laser lens fragmentation step. It is important to note that a low-energy femtosecond laser plat- form was utilized in this study. As such, these results may not translate to a higher-energy machine, such laser-assisted cataract surgery. J Refract Surg. 2013;29:742–7. 3. Chen H, et al. Expression of cytokines, chmokines and growth factors in patients undergoing cataract surgery with fem- tosecond laser pretreatment. PLoS One. 2015;10:e0137227. 4. Jun JH, et al. Effects of topical ketoro- lac tromethamine 0.45% on intraoperative miosis and prostaglandin E2 release during femtosecond laser-assisted cataract surgery. J Cataract Refract Surg. 2017;43:492–497. 5. Takahashi H, et al. Free radicals in phacoemulsification and aspiration proce- dures. Arch Ophthalmol. 2002;120:1348–52. Contact information Miller: miller@jsei.ucla.edu stress, prostaglandin, and cytokines: Comparisons of cataract surgery versus conventional phacoemulsification" Changes in aqueous oxidative stress, prostaglandin, and cytokines: Comparisons of low-energy femtosecond laser-assisted cataract surgery versus conventional phacoemulsification Yu-Chi Liu, MD, Melina Setiawan, BSc, Marcus Ang, FRCOph, Gary Hin Fai Yam, PhD, Jodhbir Mehta, FRCOph J Cataract Refract Surg. 2019;45(2):196–203. Purpose: To compare the aqueous oxidative stress, prostaglandin (PGE), and cytokine levels following low-energy femtosecond laser-assisted cataract surgery (FLACS) versus conventional phacoemulsification, and to evaluate the effect of non-steroidal anti-inflammatory (NSAID) on the aqueous profiles. Setting: Singapore National Eye Center, Singapore. Design: Randomized controlled trial. Methods: Thirty-five patients were randomized to receive conventional phacoemulsification in one eye and FLACS (Ziemer) in the fellow eye. Another matched prospective cohort of 35 patients was included to receive FLACS with preoperative NSAID (FLACS-N). Aqueous humor was collected after laser or at the beginning of surgery (conventional phacoemulsification), and at the end of phacoemulsification. The levels of aqueous malondialdehyde (MDA), PGE2, cytokines/chemokines/ growth factors were analyzed. Postoperative aqueous flare levels were evaluated. Results: Compared to the conventional group, the FLACS group had a significantly higher PGE2 (P=0.01) and interleukin-1 receptor antagonist levels (P=0.04). Preoperative NSAID significantly reduced the PGE2 surge (P=0.002) and mean reduction in pupil diameter (P=0.02). The MDA concentrations before phacoemulsification were 0.24±0.18, 0.51±0.41, and 0.59±0.52 μmol/L for the conventional, FLACS, and FLACS-N groups (P=0.42). After phacoemulsification, the PGE2 and MDA levels increased in all groups. The MDA induction was significantly correlated with the phacoemulsification time (P=0.002). The postoperative flare was insignificantly higher in the FLACS than conventional group. Conclusions: Compared to conventional phacoemulsification, LDV FLACS induced a significantly higher PGE2 level. The MDA and postoperative aqueous flare level were insignificantly higher. Preoperative NSAID reduced the PGE2 surge and occurrence of intraoperative miosis. The oxidative stress induced during phacoemulsification was strongly correlated with phacoemulsification time.

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